1. Field of the Invention
The present invention relates to a recording medium, a method for manufacturing same, and an inkjet recording method using same.
2. Description of the Related Art
An inkjet apparatus has a simple structure, and high-quality image recording can be conducted by inkjet recording performed using the inkjet apparatus. The viscosity of the ink used for inkjet recording is adjusted to a range from about several mpa·s to about 30 mPa·s and the ink is designed to have a surface tension of about 20 mN to about 40 mN/m, so that the ink can be ejected from an inkjet head.
The ink usually includes 50% to 90% by mass ink solvent so as to obtain the ink viscosity within the aforementioned range. Examples of suitable ink solvents include water, organic solvents, oils, and photopolymerizable monomers. From the standpoint of environmental compatibility, water is most often used. Further, a high-boiling solvent such as glycerin is generally used as an ink solvent in order to prevent an ejection nozzle of the inkjet head from being clogged due to drying of the ink solvent.
On the other hand, where a large amount of ink solvent is present on a recording medium where an ink image has been formed, image bleeding and mixing of colors caused by the large amount of ink solvent can easily occur. For this reason an inkjet special paper 200 (see FIG. 5) having on the surface thereof a solvent absorbing layer (ink accommodating layer) that has a thickness of about 20 μm to 30 μm and is capable of absorbing an ink solvent is used as a recording medium, thereby preventing the occurrence of image bleeding and color mixing.
In the case of an aqueous ink using water and the ink solvent, the water penetrates into the base paper during recording, thereby causing paper deformation such as curling. However, where a solvent-absorbing layer 22 is present on a base paper 21, as shown in FIG. 5, water is prevented from penetrating into the base paper and paper deformation can be inhibited.
In particular, when graphical images with a high image density and a high image surface area ratio are to be formed, the amount of ink per unit surface area on the recording medium increases, and the solvent absorbing layer can hardly prevent the ink solvent from penetrating into the base paper. For this reason, water-resistance paper (for example, laminate paper) that is covered with a resin layer using a polyolefin or the like is typically used (for example, see JP-A Nos. 2005-238829 and 2005-96285).
However, inkjet technology is not only used in connection with office printers and home printers. In recent years, it has been applied to the field of commercial printing. In commercial printing, printed sheets are required to have an appearance similar to that of general printing paper, rather than a surface, such as that of a photograph, that completely blocks penetration of ink solvent into base paper. However, the range of properties such as surface gloss, texture and stiffness is limited when a recording medium has a solvent absorption layer with a thickness as large as from 20 μm to 30 μm. Therefore, application of inkjet techniques in commercial printing has been limited, for example, to posters and vouchers, with respect to which the restrictions on surface gloss, texture, stiffness and the like are tolerable.
Further, the presence of a solvent absorbing layer and a water-resistant layer increases the cost of recording medium, thereby placing additional limitations on the application thereof.
Resin-coated paper for recording that is coated with a polyolefin resin including an antistatic agent is known as a recording paper with good pick strength during recording and good conveying ability during printing (for example, see JP-A No.9-109339). Further, lightweight printing paper having a coating layer including an antistatic agent and having a surface resistivity is known as recording paper that bears no electric charges in the printing and drying process, despite a small metric weight thereof, and does not require humidification as an antistatic measure (for example, see JP-A No. 2003-278096).